The present invention relates to filters and more particularly air filters employed in association with heat engines such as explosion engines for a motor vehicle.
As is conventional for the feeding of heat engines such as automobile engines employing essentially air as a comburent which is mixed with a fuel such as volatilized petrol or gasoline, the air is filtered in such a manner as to remove foreign particles which are in particular abrasive and liable to damage by scratching within time in particular the pistons and cylinders.
The air filters for this type of engine are well known in the art.
As an illustration, there will be mentioned the European patent application EP 0 152,513. The air filter described in this document comprises a cylindrical body, closed by a detachable cover, in the chamber of which there is placed in a detachable manner a filtering cartridge which may be cleaned and changed when it is clogged. The filtering cartridge is in the form of an annular assembly disposed in the chamber of the body of the filter. This filter body is provided with a tangential inlet nozzle and an axial central outlet nozzle. As is explained in this document, the cover which closes the chamber of the body is maintained in position by means of a nut having lugs or a wing nut and a washer, both of which are mounted on a screw-threaded rod.
Air filters, which are remarkably well illustrated in this document, are such that, for the purpose of proceeding to the cleaning or the exchanging of the filtering cartridge, it is first of all necessary to unscrew the screws or nuts which maintain the cover on the chamber of the body and then remove the cover before being able to reach the filtering cartridge and the sealing element between the body and the cover for dismantling the cartridge. When the filtering cartridge been cleaned or replaced by a new cartridge and the latter has been placed in the chamber, the sealing element and cover must be put back and the cover must be fixed in position by putting back the nut and washer which must then be tightened.
All these operations must be carried out with a certain strictness. In particular, the sealing element or elements must be correctly placed in position and if necessary replaced. Indeed, if this is not done or badly done, a reduction in the performance of the engine or even a shortening of its life may be observed.
It will be understood that such operations require specialized personnel and tooling and that they are subject to error when placing the parts back in position, or elements may be lost, for example the washers and screws or nuts might escape and drop into the outlet nozzle. These elements are then liable to obstruct the carburetor and even damage the engine itself if they manage to reach the engine.